Method for manufacturing ammonia synthesis catalyst, and method for manufacturing ammonia

Abstract

Provided is a method for manufacturing a catalyst with which it is possible to obtain a supported metal ammonia synthesis catalyst, in which there are restrictions in terms of producing method and producing facility, and particularly large restrictions for industrial-scale producing, in a more simple manner and so that the obtained catalyst has a high activity. This method for manufacturing an ammonia synthesis catalyst includes: a first step for preparing 12CaO.7Al2O3 having a specific surface area of 5 m2/g or above; a second step for supporting a ruthenium compound on the 12CaO.7Al2O3; and a third step for performing a reduction process on the 12CaO.7Al2O3 supporting the ruthenium compound, obtained in the second step. This invention is characterized in that the reduction process is performed until the average particle diameter of the ruthenium after the reduction process has increased by at least 15% in relation to the average particle diameter of the ruthenium before the reduction process.

The invention claimed is: 
     
       1. A method for manufacturing an ammonia synthesis catalyst, the method comprising:
 a first step of preparing 12CaO.7Al 2 O 3  having a specific surface area of 5 m 2 /g or more; 
 a second step of supporting a ruthenium compound on the 12CaO.7Al 2 O 3 ; and 
 a third step of performing reduction process on the 12CaO.7Al 2 O 3  on which the ruthenium compound is supported (hereinafter referred to as ruthenium-supported C12A7) obtained in the second step, 
 wherein the reduction process is carried out until an average particle diameter of a ruthenium after the reduction process increases by 15% or more with respect to an average particle diameter of a ruthenium before the reduction process. 
 
     
     
       2. The method for manufacturing an ammonia synthesis catalyst according to  claim 1 , wherein a specific surface area of the ruthenium-supported C12A7 after the reduction process step is 5 m 2 /g or more. 
     
     
       3. The method for manufacturing an ammonia synthesis catalyst according to  claim 1 , wherein in the first step, preparing 12CaO.7Al 2 O 3  is carried out by a hydrothermal synthesis method, a sol-gel method, a combustion synthesis method or a co-precipitation method. 
     
     
       4. The method for manufacturing an ammonia synthesis catalyst according to  claim 1 , wherein in the second step, supporting the ruthenium compound is carried out by an impregnation method or a vapor deposition method. 
     
     
       5. The method for manufacturing an ammonia synthesis catalyst according to  claim 1 , wherein in the step of performing reduction process, the reduction process is carried out by using a gas containing hydrogen. 
     
     
       6. The method for manufacturing an ammonia synthesis catalyst according to  claim 1 , the method further comprises, following the first step, a step of molding the 12CaO.7Al 2 O 3  obtained in the first step. 
     
     
       7. The method for manufacturing an ammonia synthesis catalyst according to  claim 1 , the method further comprises, following the second step, a step of molding the ruthenium-supported C12A7 obtained in the second step. 
     
     
       8. The method for manufacturing an ammonia synthesis catalyst according to  claim 1 , wherein the ammonia synthesis catalyst comprises at least an alkali metal atom or an alkaline earth metal atom. 
     
     
       9. A method for manufacturing ammonia, comprising:
 a first step of preparing 12CaO.7Al 2 O 3  having a specific surface area of 5 m 2 /g or more; 
 a second step of supporting a ruthenium compound on the 12CaO.7Al 2 O 3 ; 
 a third step of performing reduction process on the 12CaO.7Al 2 O 3  on which a ruthenium compound is supported (hereinafter referred to as ruthenium-supported C12A7) obtained in the second step, wherein the reduction process is carried out until an average particle diameter of a ruthenium after the reduction process increases by 15% or more with respect to an average particle diameter of a ruthenium before the reduction process; and 
 a step of producing ammonia by contacting a gas containing nitrogen and hydrogen with an ammonia synthesis catalyst which is obtained by the reduction process in the third step. 
 
     
     
       10. The method according to  claim 9 , wherein in the step of performing reduction process, the reduction process is performed by using a gas containing hydrogen. 
     
     
       11. The method according to  claim 9 , wherein in the step of performing reduction process, the reduction process is performed with a gas containing hydrogen and nitrogen. 
     
     
       12. The method according to  claim 9 , wherein the ammonia synthesis catalyst comprises at least an alkali metal atom or an alkaline earth metal atom. 
     
     
       13. The method for manufacturing an ammonia synthesis catalyst according to  claim 1 , wherein
 the reduction process is carried out at atmospheric pressure, and the time of the reduction process is 20 hours or more, or 
 the reaction pressure is carried out at 1 MPa or more, and the time of the reduction process is 5 hours or more.